The present invention relates to a method and apparatus for automatically exchanging the roving bobbin of a ring spinning machine. More specifically, the present invention relates to a method and apparatus for exchanging roving bobbins by means of a movable service unit which can be moved to the spinning stations of a ring spinning machine.
During a yarn spinning process, a ring spinning machine draws roving from a supply bobbin suspended above a spinning bobbin onto which spun yarn is wound. Oftentimes, the roving is simultaneously fed from a second bobbin suspended adjacent the first bobbin. The roving on each bobbin eventually is completely drawn from its supply bobbin and, ideally, a new, full roving bobbin is in position to be quickly substituted for the empty bobbin so that little or no disruption in the spinning process occurs. To this end, spare roving bobbins are typically suspended above and adjacent to the roving bobbins from which yarn is already being drawn. To exchange a full roving bobbin for an empty bobbin, a service unit is movable to a station at which the empty roving bobbin is suspended for operation in conjunction with apparatus coupled to the ring spinning machine to effect an exchange of the bobbins.
In European patent publication A 0 213 962, a service unit for exchanging bobbins on a ring spinning machine is disclosed. The service unit includes two gripping elements which can be moved to support and transfer a full bobbin suspended on a spare bobbin frame or an empty bobbin suspended on the ring spinning machine and whose movement must be coordinated. However, the extent of the equipment necessary to operate two gripping elements and to coordinate their movements adds considerable complexity to this type of roving bobbin exchange apparatus. Furthermore, additional equipment is required to move the innermost row of roving bobbins to a position in which the apparatus can access the bobbins.
In German Pat. No. 32 46 463 A1, a movable service unit is disclosed for delivering full roving bobbins to the spare bobbin frame of a ring spinning machine. In German Pat. No. 28 11 128 C2, a movable service unit is disclosed for removing a package wound on the spindle bank of a ring spinning machine and for inserting a new core on the spindle of the spindle bank to continue the spinning process. However, the need exists for a method and apparatus for exchanging empty or nearly empty bobbins on a ring spinning machine for full roving bobbins with minimum interruption to the spinning process.